The details as far as I understand... subject to correction.
The Ref. 3757 IWC Spitfire Perpetual Calendar was made for Sincere Watch Ltd on the occasion of their 50th Jubilee anniversary. 50 pieces were made with 25 each in silver or black dial, 5 examples of each were made on steel bracelet.
Movement: IWC Caliber 79261, automatic self-winding
Dimensions: 42mm x 52mm x 16mm
Glass: Anti-glare coated sapphire crystal
Hands: Steel with luminous
Dial: 2 tone silvered with applied steel Arabic numbers and a luminous arrow at 12
Case: Brushed steel with polished bezel ring. Signed screw-lock crown with round pushers. Screw-lock back.
Strap: stainless steel IWC pilot’s bracelet
Functions: Automatic, subsidiary seconds, time, date, chronograph, moon phase, perpetual calendar, and and full year indicator
Grand Complications: developed for the Da Vinci in the 1980s
IWC have not released a regular production of this watch to date
Purchased new in Singapore and for the most part, it's an everyday wear.